Monday, January 7, 2013

Breaking Bread, Not Just For Humans

People have been sharing food with strangers since ancient
days, offering up the household's finest fare to mysterious travelers. Think
Abraham and the three men of Mamre in the Bible and the folks who take in
strangers after natural disasters like Hurricane Sandy. That deep tradition of
generous hospitality has long been thought uniquely human.

If so, then bonobos, those gregarious African apes, may be
more like us than we thought. So says Nancy Shute, of NPR.

"The pairs that are unfamiliar with each other are the
ones that shared most often," says JingZhi Tan, a graduate student at Duke
University who tested bonobos' penchant for sharing food and discovered that
they not only share with strangers, they even offer their fruit and nuts to an
unfamiliar bonobo faster than they will feed one they know well.

Bonobos, like humans, are acutely social, and often eat
together. With both species, it works. Children and other vulnerable relatives
get fed, social ties are strengthened and alliances formed.

But humans also developed a rich tradition of feeding
strangers, one that's embedded in religion and literature – the xenia of
ancient Greece, promoted by Zeus, the god of travelers. Back then there were
practical reasons for selfless hospitality. It allowed people to travel far
from home in the days long before Holiday Inns and drive-throughs. Stingy hosts
were reviled, but so were guests who failed to be properly grateful. When Paris
made off with his host's wife, Helen, in the Iliad, that faux pas kicked off
the Trojan War.

But could hospitality be important to apes? Tan and his
colleagues at Duke had done experiments with bonobos two years ago that showed
that bonobos would share food with unrelated bonobos, rather than hoard it. Now
they wanted to find out just how far that spirit of sharing went. So they
created a series of experiments with bonobos living in a sanctuary in Kinshasa,
Democratic Republic of Congo.

The series of experiments gave bonobos the ability to decide
whether they would share their apples, bananas, papayas, and peanuts by giving
them control over doors in a room. (See how the researchers did it in this
video.)

In the first experiment, the scientists created a setup
where one bonobo was put in a room with food. That bonobo could choose to open
two doors leading to two other rooms – one housing a friend, the other, a
stranger.

All of the bonobos opened a door to let in another, rather
than dine alone. And nine of the 14 animals chose dining with the stranger over
the familiar face – the ape equivalent of a restaurant's communal table.

What's more, when the familiar bonobo was invited to join
the feast, it was almost always by the stranger, who would have considered that
bonobo a new face. None of the animals fought over the food, and there was
quite a bit of the friendly genital rubbing that's made bonobos renowned in
animal behavior-land.

Then the scientists tweaked the layout. In another
experiment, the bonobos were isolated in separate cages, with food in a
compartment in between. Offered the option of sharing the food without physical
contact, not one of the seven bonobos tested pulled a rope that would have let
another reach through to the food. The results were published online in the
journal PLoS One.

So it looks like if you're a bonobo, sharing food is only
worth it if it's a social event. Bonus points if you're meeting someone new.
It's fascinating behavior, but the researchers say it's not clear that this is
altruism. "If you're being nice to a stranger, it's not necessarily
unselfish," Tan told The Salt. It's easy to see the benefits to humans in
sharing a meal with a stranger, even in modern times. Good conversation, future
business partners, a broader social network – maybe even romance. Perhaps
bonobos see those potential payoffs in a meal shared, too.